Adjustable Convective Heat Transfer Flue for Ash and Dew Control
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Solution Overview
Problem
The existing convective heat transfer flue in boilers suffers from non-adjustable flue gas direction, velocity, and heating surface area, leading to ash deposition and dew formation due to constant vortex regions and temperature fluctuations, particularly during startup or low-load operations.
Innovation Solution
A controllable multidirectional-flow convective heat transfer flue with adjustable shutters or sliding gates between heating surface groups and at inlet/outlet, allowing for 90-degree rotation or sliding movement, enabling alternating gas flow directions and partial surface sweeping to prevent ash deposition and dew formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the flue gas advances in a fixed straight cylindrical path with non-adjustable direction, then the structure is simple, but ash deposition occurs due to constant vortex regions on the backward surfaces of heat transfer tubes
Solution Approach 1:
The patent introduces adjustable guide walls that can change the flow direction of flue gas dynamically. The guide walls are divided into multiple sections that can be independently adjusted to alter the gas flow path, transforming the fixed straight cylindrical path into a variable multidirectional flow path. This dynamic adjustment prevents constant vortex regions and reduces ash deposition on heat transfer tubes.
Solution Approach 2:
The guide walls are segmented into multiple adjustable sections, each capable of independent rotation or adjustment. This segmentation allows precise control over different portions of the gas flow, enabling the creation of varied flow patterns and eliminating stagnant vortex zones that cause ash accumulation.
2Power
If the flue gas velocity is non-adjustable and maintained at rated velocity, then the heat transfer efficiency is optimized, but dew formation occurs due to excessive temperature reduction in trailing portions of heating surface groups
Solution Approach 1:
The patent enables dynamic adjustment of flue gas velocity through controllable guide walls that regulate flow distribution. By adjusting the guide wall angles, the gas velocity can be varied along different paths and at different times, allowing the system to maintain optimal velocity for heat transfer while preventing excessive cooling that leads to dew formation in trailing portions.
Solution Approach 2:
Different sections of the guide walls can be adjusted independently to create local variations in gas flow characteristics. This allows specific areas with higher cooling rates to receive adjusted flow patterns that prevent excessive temperature reduction, while other areas maintain conditions optimal for heat transfer efficiency.
3Area of stationary object
If all convective heating surface groups are swept by low-temperature flue gas during startup or low-load operation, then the heating surface area is maximized, but continuous significant temperature reduction causes dew on the tail heating surface
Solution Approach 1:
The patent allows selective activation of different heating surface groups based on operational conditions. During startup or low-load operation, the guide walls can be adjusted to direct flue gas through only certain heating surface groups, avoiding the continuous sweeping of all surfaces. This partial action prevents excessive temperature reduction and dew formation on distant tail heating surfaces while still providing necessary heating.
Solution Approach 2:
The system dynamically adjusts the distribution of flue gas across heating surface groups based on load conditions. During startup or low-load operation, the guide walls redirect flow to activate only the necessary portion of heating surfaces, matching the heating demand and preventing over-cooling that leads to dew formation.
4Device complexity
If the flue gas flow path and heating surface area are non-adjustable, then the device structure is simple, but the system cannot track load variations during startup or low-load operation
Solution Approach 1:
The patent introduces adjustable guide walls with multiple sections that can be independently controlled to vary the flue gas flow path and the portion of heating surface area activated. This dynamic adjustability enables the system to adapt to different load conditions during startup, partial load, and full load operation, providing load tracking capability while maintaining relatively simple structural elements.
Solution Approach 2:
The adjustable guide walls serve multiple functions: they control flow direction, regulate gas velocity, select which heating surface groups are active, and enable load tracking. This multi-functionality allows a single structural element to address multiple operational requirements without proportionally increasing system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively resists ash deposition and dew formation by altering gas flow paths and velocities, maintaining stable temperatures and preventing excessive cooling during startup or low-load operations, thus optimizing boiler performance and load tracking.
Implementation Method 1
flue gas enters the convective heat transfer flue via a flue gas inlet of the convective heat transfer flue and advances to a flue gas outlet of the convective heat transfer flue
Implementation Method 2
flue gas-water heat transfer tubes arranged in the convective heating surface groups
Data Source
AI summary
A convective heat transfer flue, including a flue wall (1) and convective heating surface groups (2) arranged inside the flue wall (1), shutters adjustable through 90 degrees or sliding gates (9) are arranged between adjacent convective heating surface groups and at a flue gas inlet and a flue gas outlet of the convective heat transfer flue. The proposed flue solves the problems of fouling within back-flow vortex regions of heat transfer pipes, and condensation on heating surfaces in the tail of the flue wall (1), as well as being beneficial for boiler start-up and load adjustment thereof.